The latest indirect measurement of the top quark pole mass is surprisingly precise (exceeding the precision of the world average in a single measurement) despite the method used, which has historically had large error bars. The Particle Data Group world averages are as follows:
This will probably drag up the world average a little bit, to about 172.7 GeV.
We present an indirect determination of the top-quark pole mass mt within a global analysis of parton distribution functions (PDFs), based on the public NNPDF framework.
We consider a wide range of measurements, including both single- and double-differential observables, computed at NNLO QCD accuracy with EW corrections, and analyse their individual as well as combined impact on the joint (α(s),m(t)) parameter space, while accounting for PDF evolution up to approximate N3LO QCD accuracy with QED corrections. We account for missing higher order QCD uncertainties by default.
Unique to our analysis are the inclusion of, first, toponium contributions around the tt¯ threshold, second, state-of-the-art constraints on αs from the lattice, and finally, a detailed sensitivity study of the various ATLAS and CMS differential cross-section measurements at 8 and 13 TeV. We demonstrate explicitly how a combined determination requires the refitting of the PDFs in order to correctly correlate uncertainties.
We find mt = 172.80 ± 0.26 GeV at approximate N3LO QCD including NLO QED, EW and toponium corrections.
Richard D. Ball, Jaco ter Hoeve, Roy Stegeman, "A Determination of the Top Mass from a Global PDF Analysis" arXiv:2603.28865 (March 30, 2026).
Another new paper on top quark physics (with an abstract devoid of much of an interesting description of the paper) confirms that:
(1) the experimentally measured top quark-antitop quark pair production rates are consistent with the Standard Model expectation,
(2) toponium has been discovered by both the ATLAS and CMS experiments at the Large Hadron Collider (LHC), and
(3) the Higgs field Yukawa of the top quark is experimentally confirmed to be not more than 2.1 times the Standard Model expectation (the coupling should be proportionate to the top quark's pole mass in the Standard Model).
4 comments:
thought
https://indico.global/event/15553/contributions/145982/
https://cds.cern.ch/record/2957825/files/X17Workshop_Trento_2026.pdf
The first: somebody built an experiment which hasn't done anything yet. Ho hum.
The second: page 9 is most interesting, since all quantum reactions are time reversible. If X17 can decay to a positron-electron pair, then it follows that X17 should be produced in positron-electron collisions at all energies from 17 MeV and up, which there is lots and lots of data on, none of which show the existence of X17.
The protophobic model is also a huge, ill-motivated hypothesis.
It looks like there is absolutely no signal so far at LHCb.
Also, a particle with a mean lifetime of 5 ps or less just can't be a viable dark matter constituent.
In short X17 remains a dubious hypothesis, supported by 2 sigma tensions at best, with possible SM explanations, that is ill-motivated.
It's not going to be found.
many processes can decay to a positron-electron pair, so there is a problem with noise to signal ratio
Probing the ATOMKI X17 vector boson using Dalitz decays
Chien-Thang Tran, Mikhail A. Ivanov, Anh-Tuyet T. Nguyen
Recent anomalies observed in nuclear transitions of , , and by the ATOMKI collaboration may hint at the existence of a vector boson with a mass around 17 MeV, referred to as X17. If it exists, this boson would also affect similar processes in particle physics, including the Dalitz decays of vector mesons. Recently, the BESIII collaboration measured the Dalitz decay for the first time and reported a excess over the theoretical prediction based on the vector meson dominance (VMD) model. This excess may be another signal of the X17. In this study, we investigate the possible effects of the X17 on the Dalitz decays , , and . The required hadronic form factors are calculated within the framework of our covariant confined quark model, without relying on heavy quark effective theory or the VMD model. We present predictions for the Dalitz decay widths and the ratios within the Standard Model and in several new physics scenarios involving modifications due to the X17. Our results are compared with other theoretical calculations.
Comments: 21 pages, 6 figures, typos corrected, references added. To be published in Chinese Physics C
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:2506.23372 [hep-ph]
34 citation
Recently, the BESIII collaboration measured the Dalitz decay for the first time and reported a excess over the theoretical prediction based on the vector meson dominance (VMD) model
3.4 sigma over standard models predictions
don't you think it's exciting that dozens of experiments and thousands of HEP are attempting to verify or disapprove x17, including LHC CERN in our lifetime ?
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